Flip the official Linux x64 chrome builder from GYP to GN.
Flip the official Linux x64 chrome builder from GYP to GN.

R=kerz@chromium.org
BUG=530733

Review URL: https://codereview.chromium.org/1366093005

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#352171}

axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk